1. Field of the Invention
This invention relates generally to tobacco and tobacco smoking materials and methods of making same. More particularly, the present invention relates to the materials and methods that provide tobacco materials with reduced lignin and nitrogenous content.
2. Description of the Related Art
Tobacco material contains various nitrogenous compounds that can adversely affect its smoke quality. Among these nitrogenous compounds are proteins, amino acids and certain alkaloids, such as nicotine, nornicotine, anabasine and anatabine. The smoke quality of tobacco is adversely affected particularly by heterocyclic and aromatic amines, and tobacco specific nitrosamines (TSNA), as well as other compounds formed by pyrolysis or transfer of these nitrogenous compounds. Tobacco processing sometimes includes steps in which the nitrogen content of the tobacco is reduced so as to improve the smokability of the tobacco. However, nitrogenous compounds are difficult to extract from cured tobacco lamina, stem, and fiber cell walls. Many of the current processes used to reduce nitrogen content in tobacco material employ enzymatic compounds and microbial agents to break down the proteins and other nitrogen-containing compounds within the tobacco. However, disadvantages arise from the use of such enzymatic compounds and agents. In particular, enzymes are expensive, pH sensitive and degrade proteins into amino acids which tend to remain with the tobacco material. It is also thought that enzymatic compounds leave residues on tobacco material after processing. Furthermore, microbial agents used in treating tobacco tend to cause unwanted reactions that generate undesirable byproducts. Moreover, in many of these tobacco treatments, the tobacco disintegrates or easily breaks into small pieces.
Therefore, there is a need to provide a process by which the nitrogen content of tobacco material may be reduced without leaving residues or undesirable by-products and the break-down of tobacco solid materials is reduced.
The present invention relates to a method for providing a tobacco material having a reduced lignin and nitrogenous content. The tobacco material in the form of flue cured and burley whole leaf lamina as well as stems, fines, or scraps is contacted with an aqueous solvent. The resulting liquid extract is separated from a tobacco fiber portion. The tobacco fiber portion is then contacted with a solution containing an alkali metal hydroxide, such as sodium hydroxide and/or potassium hydroxide, and hydrogen peroxide. This solution is also separated from the tobacco fiber portion. The tobacco fiber portion may then be washed, refined and further processed for use in smoking articles, such as cigarettes. The reduction of lignin and nitrogenous compounds in the tobacco material provides for improved smokability and a reduction in nitrogen containing pyrolitic products emitted from smoking articles which contain the tobacco material.
It is an object of the present invention to provide a tobacco product with reduced levels of lignin and nitrogenous compounds.
It is another object of the present invention to provide a method of making a tobacco product with reduced levels of lignin and nitrogenous compounds.
It is a further object of the present invention to provide a method of treating tobacco which minimizes the break-up of tobacco solid materials.
More particularly, the present invention is directed to a method for reducing the lignin and nitrogenous content of tobacco material, including cured tobacco whole leaf, fines, scraps, stems and lamina, as well as burley leaf and stem, comprising the steps of contacting tobacco material with a first aqueous solvent, such as water, at a temperature of about 60xc2x0 C. to 8xc2x0 C. for about 0.5 to 1 hours; separating an aqueous tobacco extract from a tobacco fiber portion; contacting this washed tobacco fiber portion with a solution containing from 1% to 5% (weight/weight) alkali metal hydroxide and from 2.5% to 12% (weight/weight) hydrogen peroxide at a temperature of about 25xc2x0 C. to 120xc2x0 C. for about 0.5 to 4 hours; and, separating the resulting solution from the tobacco fiber portion. The resulting tobacco product is then dried and used in the manufacture of cigarette articles. Alternatively, the extract or a portion thereof, may be added to the tobacco product before drying.
A better understanding of the present invention will be realized from the hereafter processes and the Examples following such description.